Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support

Pollinator-Mediated Interactions between a Pathogenic Fungus, Uromyces pisi (Pucciniaceae), and Its Host Plant, Euphorbia cyparissias (Euphorbiaceae)

Monika Pfunder and Barbara A. Roy
American Journal of Botany
Vol. 87, No. 1 (Jan., 2000), pp. 48-55
Stable URL: http://www.jstor.org/stable/2656684
Page Count: 8
  • Read Online (Free)
  • Download ($12.00)
  • Subscribe ($19.50)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Pollinator-Mediated Interactions between a Pathogenic Fungus, Uromyces pisi (Pucciniaceae), and Its Host Plant, Euphorbia cyparissias (Euphorbiaceae)
Preview not available

Abstract

The plant Euphorbia cyparissias is commonly infected by rust fungi of the species complex Uromyces pisi. When infected, E. cyparissias is unable to flower, but instead is induced by the fungus to form pseudoflowers. Pseudoflowers are rosettes of yellow leaves upon which the fungus presents its gametes in a sweet-smelling fungal nectar. We hypothesized that the fungi, as they are heterothallic, are dependent on insect visitation to cross-fertilize their mating types. We confirmed that insects are required with an insect exclusion experiment. We further hypothesized that pseudoflowers of U. pisi interact with uninfected true host flowers through insects during their period of co-"flowering" in early spring. We conducted artificial array experiments in the field to test whether the two species share insects and whether they influenced each other's insect visitation. Insects moved between true flowers and pseudoflowers, but true flowers received more visits over all. Pseudoflowers and true flowers did not influence each other's visitation rates in mixtures. However, shorter visits were observed on pseudoflowers in mixtures than monocultures, suggesting that true flowers might be competitors for pseudoflowers. Further experiments are needed to determine whether the similarity of pseudoflowers to true flowers is adaptive.

Page Thumbnails

  • Thumbnail: Page 
48
    48
  • Thumbnail: Page 
49
    49
  • Thumbnail: Page 
50
    50
  • Thumbnail: Page 
51
    51
  • Thumbnail: Page 
52
    52
  • Thumbnail: Page 
53
    53
  • Thumbnail: Page 
54
    54
  • Thumbnail: Page 
55
    55